# All Questions

21,236 questions
Filter by
Sorted by
Tagged with
354 views

### Intersecting bug trail [closed]

A man picks up a huge circular dart board and shoots paintballs at it. $n$ paintballs manage to hit it. They are random and point-sized, for the purpose of this question. A bug is somewhere on the ...
699 views

### Ninety-nine non-negative numbers

Alice and Bob play the following game with $99$ numbers $M_1,\ldots,M_{99}$. In the beginning, the $99$ numbers take the values $1,2,4,8,16,\ldots,2^{97},2^{98}$. Then Alice and Bob alternatingly ...
1k views

### Where are the missing guests?

I'm Caucasian and my fiancé is Chinese - I met her on a trip to Tahiti though as chance would have it, it turned out that we actually grew up in adjacent towns in Ohio. We decided to have a very ...
494 views

### Can anyone help me remember the title to this song?

This is related to my previous question, Q: Nice song, pity about the words I have a terrible memory for the words of songs and I'm even worse when it comes to their titles. I'd really like to find ...
6k views

### Can you solve this devilish Junior Jumble?

In the game Undertale, there is a character named Papyrus who believes that the Jumble puzzle is much harder than the daily crossword. Help prove him right by trying to solve this brainteaser:
682 views

### Are there any sets of 9 numbers that can form two essentially distinct magic squares?

It's known that the numbers 1 to 9 can only form eight different magic squares, which are all rotations and reflections of each other. Is there any set of 9 distinct numbers that can form two ...
448 views

### Save the world from Dr. Mysterious

My name is ????? You must find out Dr. Mysterious's name, which is your greatest weapon against him (it gives you power over him). His slave, Mr. Useless, has sent you some information but it is ...
277 views

### Strange implications with $aN$, $eF$ and $gH$

Given the implications $$aN\implies S$$ $$eF\implies I$$ $$gH\implies M$$ could you please complete the following implication: $$nS\implies ?$$ (The answer is one of the letters $T$, $A$, $L$,...
242 views

Eighteen coins are arranged in a circle. In the beginning, all eighteen coins show tails. The following two moves are allowed: Simultaneously flipping over four consecutive coins (so that tails ...
407 views

### The Witches Have Overdone It

Alice the Witch had a great night last night. She'd had a Halloween night house party with five of her closest friends from Witch College that she hadn't seen for ages. They had been drinking and ...
260 views

### Mixed Backwards Hangmen

My previous backward hangman (created originally by Alex, see here), was still solved too quickly, so I thought I'd make another tweak to make it a bit more tricky. This time, whatever the bizarre ...
434 views

### The smallest value on the blackboard

The square numbers $1^2, 2^2, 3^2, 4^2, \cdots, 100^2, 101^2$ are written on the blackboard. Each minute any two numbers are wiped out, and the absolute value of their difference is written instead....
457 views

385 views

### How can our secret agent produce a cryptographically secure random number?

Secret Agent Michael Scarn enters his hotel room, only to find it having been ransacked. He needs to send an encrypted message to his handler notifying them that his cover has been compromised. In ...
958 views

### Self referential puzzles - follow-up

https://puzzling.stackexchange.com/questions/23554/self-referential-puzzles made me wonder. How many solutions are there to the below box when multiple digits are allowed? I don't know the answer ...
286 views

### Yes, I *can* be more metaphorical

Same deal as previous post. One real world source; answers must explain each line and what they all mean when put together. Additionally amongst the mortality, while the final several cadavers ...
2k views

### Another curious incident in the flea circus

The ringmaster of a flea circus puts four fleas $A$, $B$, $C$, $D$ on four different points in the plane that form the corners of a square. Whenever the ringmaster shouts "Hop!", one of the four ...
470 views

### Could you *be* any more metaphorical?

The following, apparently random list of seemingly random nonsense is a metaphorical interpretation of something that exists in the real world. What is it? As always, go line by line. But once you ...
The ringmaster of a flea circus puts three fleas $A$, $B$, $C$ on three different numbers on the real number line, so that flea $B$ sits exactly in the middle between $A$ and $C$. Whenever the ...
Two plane mirrors facing each other are arranged at $60^o$ to each other. A point is located on the angle bisector. How many images of the point are there?